1. Field of the Invention
The present invention relates in general to cleaning and purifying compositions and, more particularly, to compositions for cleaning and purifying process water that results from the refinement of petroleum.
2. Background Art
Wastewaters from petroleum refining consist of cooling water, process water, storm water, and sanitary sewage water. Process water accounts for a significant portion of the total wastewater. Process wastewater arises from desalting crude oil, steam stripping operations, pump gland cooling, product fractionator reflux drum drains and boiler blowdown. Because process water often comes into direct contact with oil, it is usually highly contaminated. The process water must be treated so that it may either be reused in parts of the refinery or discharged through the process area rainwater treatment system. Treatment of process water must effectively remove napthenic acid, separate out any hydrocarbons, and effectively drop out any solids. Napthenic acid, obtained as a byproduct of petroleum refining, is a mixture of carboxylic acids that possess cyclopentane rings and is slightly soluble in water. Methods of treatment of refinery process water have been known in the art for years, and are the subject of several patents, including: U.S. Pat. No. 6,536,523 entitled “WATER TREATMENT PROCESS FOR THERMAL HEAVY OIL RECOVERY;” U.S. Pat. Nos. 5,651,833 and 5,562,834 entitled “WASTE CONCENTRATION AND DESTRUCTION PROCESS;” and U.S. Pat. No. 4,274,968 entitled “PROCESS FOR THE PURIFICATION OF WATER.”
U.S. Pat. No. 6,536,523 appears to disclose the transfer of heat energy into a heated separator and re-boiler exchanger to distill oil reservoir produced water and recover distilled water and a concentrated brine or solid product.
U.S. Pat. Nos. 5,651,833 and 5,562,834 appear to disclose removing volatile organic compounds from the wastewater stream by steam stripping and then contacting a stream comprising steam and the stripped organic compounds with a catalyst at an elevated temperature so as to convert the hydrocarbon portion of the organic compounds to a mixture of hydrogen and carbon dioxide.
U.S. Pat. No. 4,274,968 appears to disclose the addition of an effective amount of chemical flocculent to the feed water and subjecting said water to flocculation; passing the flocculated water to a clarifier where suspended solids are separated from the partially purified water; adding about 1 to about 100 parts powdered activated carbon per million parts of water from the clarifier; contacting the water with said carbon in a reaction zone so as to achieve substantial reduction of contaminants in the water; separating the activated carbon from the purified water; and recycling a portion of the separated activated carbon to the clarifier effluent.
An experiment at Stanford University employed clay to purify process water, but this resulted in a new problem of contaminating the clay with hydrocarbons. None of the above-identified or any other prior-art references accomplished removal of napthenic acid, separation of hydrocarbons, and dropping of solids from petroleum refinery process water to yield water free of these contaminants.
It is therefore an object of the present invention to provide a composition (i.e. a mixture or combination of chemicals) and a method for their use that results in the treatment of petroleum refinery process water to yield purified water that is free of contaminating napthenic acid, hydrocarbons, and/or solids.